Metabolomics Creative Proteomics

Citrulline Analysis Service

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What is Citrulline?

Citrulline is a non-protein amino acid, and the conversion of glutamine in the villi of the proximal small intestine is the main source of citrulline in the circulating blood. Citrulline has physiological effects such as scavenging free radicals and anti-oxidation, improving immune system function, indicator of foreign body rejection effect, vasodilation, maintaining joint motor function, improving sexual endurance and erectile function, and stabilizing blood pressure. Citrulline has a highly specific metabolism, it cannot be digested and absorbed by the intestine or liver, and can be used as a precursor of arginine synthesized de novo in endothelial cells and immune cells. Oral citrulline facilitates the delivery of arginine to the systemic circulation, so it can be used as a protein anabolic agent in specific clinical situations. Citrulline can maintain protein homeostasis, it can stimulate the signal transduction pathway of protein synthesis in skeletal muscle, and it is a drug nutrient with great application value.

Citrulline does not contain an aromatic ring chromophore and cannot be directly detected by UV detectors. Therefore, 2,4-dinitrofluorobenzene (DNFB) derivatization reagents can be used to derive amino acids with strong UV or fluorescence absorption, and then obtain the HPLC quantitative analysis. At the same time, we can also use LC-MS to detect the citrulline content, which provides high sensitivity for its detection, uses a minimum of sample detection, and ensures rapid analysis methods and results conversion.

Creative Proteomics can provide simple and reliable reversed-phase high performance liquid chromatogram (RP-HPLC) and liquid chromatograph mass spectrometer (LC-MS) method to detect the content of citrulline and its derivatives, and can provide customers with detailed citrulline analysis reports. The method is fast, accurate, easy to operate, and the result has good linearity and accuracy.

Nitric Oxide (NO) Cycle.Figure 1. Nitric Oxide (NO) Cycle. (Allerton 2018).

Citrulline Analysis Services by Creative Proteomics

Creative Proteomics offers specialized citrulline analysis services to facilitate research in the field of citrulline metabolism and its derivatives. These services include:

1. Metabolic Analysis

Creative Proteomics employs advanced analytical techniques, such as liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS), to comprehensively analyze citrulline metabolism in biological samples. Metabolic profiling enables the identification and quantification of citrulline and its metabolic intermediates, providing valuable insights into the metabolic pathways involved.

2. Identification and Quantification of Citrulline Derivatives

Creative Proteomics specializes in the identification and quantification of citrulline derivatives, including citrullinated proteins, citrulline-containing peptides, and citrulline metabolites. These derivatives play critical roles in various biological processes and serve as potential biomarkers for diseases. Creative Proteomics can accurately identify, characterize, and quantify citrulline derivatives, facilitating your study in different biological contexts.

3. Citrulline-Arginine Ratio Analysis

The citrulline-arginine ratio is a significant parameter for understanding the activity of enzymes involved in citrulline metabolism. Creative Proteomics offers precise measurement and analysis of the citrulline-arginine ratio, providing you with valuable data to assess metabolic alterations and disease conditions.

Advantages of Our Citrulline Analysis Service

  • Short analysis cycle and low cost
  • The method is stable, reliable and highly sensitive analysis report
  • One-stop service and meet diverse testing needs
  • Wide application range and simplified operation process
  • Abundant biological analysis resources and first-class analysis platform

Service Workflow

We use DNFB as the pre-column derivatization agent, separated by HPLC, and detected by UV detector. The derivatization reaction is thorough, and the derivative product DNP-citrulline is stable. Excessive DNFB has no interference to the quantitative determination of citrulline, the analysis cycle is short, and the application range is wide. LC-MS is used for detection, quantitative analysis results of trace sample substances.

Citrulline analysis service workflow.Figure 2. Citrulline analysis service workflow.

Detection method: RP-HPLC or HPLC-MS

Mobile phase: mobile phase A is acetonitrile-water solution (1:1), mobile phase B is a buffer salt solution of 50 mmol·l-1 potassium dihydrogen phosphate plus 1‰ phosphoric acid

Elution mode: linear gradient elution

Detection wavelength: 360nm

Resolution: 0.25-100 μg·mL-1

Precision: 1.98%

Average sample recovery rate: 87.45%

Repeatability: 1.55%

Injection volume: 20 μl

Flow rate: 1.0 ml/min

Analysis content:

  • Standard straight-line drawing
  • Investigation of sample preparation methods and sample derivatization conditions
  • Selection of chromatographic conditions and detection wavelength
  • Chromatogram raw image and data collection
  • Determination of citrulline and its derivatives

Sample Preparation

  • Blood/plasma: 500ul/sample
  • Bile: 10ul/sample
  • Urine: 1ml/sample
  • Tissue: 200mg/sample
  • Cells: 1x107/sample
  • Feces: 500mg/sample
  • Sample storage and transportation: Store in liquid nitrogen or -80°C, and transport on dry ice.

Number of biological replicates: At least 6 biological replicates for plant samples, and at least 10 biological replicates for animal samples

The samples include multiple sample types such as animals, plants and microorganisms, please contact us for details.


  • Complete experimental protocol
  • Chromatographic conditions and peak analysis
  • Parameters of chromatography and mass spectrometry
  • Chromatography and mass spectrometry raw data files
  • Analysis report of identification and content determination of citrulline and its derivatives
  • Customized analysis report

We use simple and reliable RP-HPLC and LC-MS method to detect the content of citrulline, and obtain high-accuracy and highly selective analysis reports, which will help researchers to speed up the research on the molecular mechanism of citrulline and its derivatives. These studies can realize its application in food and medical related fields. Creative Proteomics has professional analysis engineers and reliable biological analysis technology, which can meet your testing needs for multiple sample types.


  1. Allerton T D, Proctor D N, et al. Irving BA. l-Citrulline Supplementation: Impact on Cardiometabolic Health. Nutrients. 2018;10(7):921.
  2. Rashid J, Kumar S S, et al. Therapeutic Potential of Citrulline as an Arginine Supplement: A Clinical Pharmacology Review. Paediatric Drugs. 2020;22(3):279-293.
For Research Use Only. Not for use in diagnostic procedures.


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